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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5c2ad7b4d0f0e50ecb2a98f7d00ef4935b2400ef8597e0c1ce53cb9764d5c71' 
  AND token = 'RUPXwRzGTq6CoTik+FkpZLwYa49tMCNnxjriDfQeyUk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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