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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b8e37a12bd3b814311f81bdb482273f4376833666e2570d9b9b6752d2fd3116' 
  AND token = 'c6XFdrXR6WeB2fcGR6AfDLkIKUYT4JBQUNd+wzN300M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}