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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1756a5ccb37131ade96bb1a468ff68573b8885bcc3ca0cf3b00b2a768b83bb43' 
  AND token = 'dfBKby9aVVXbNAhNXnd6JYVF5Q6hiLB8yo+xwPzzicY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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