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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '921eb44a3edd0d5e04a240f81b240441ccb347cbf567b26cc6740e7d0914ce38' 
  AND token = 'LHN1u5KdSuyURW5q7bFhqj3z+/hGwxeIUJqM3xvL67s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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