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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c3381e1e889b7bf07e2f48c3f8cb835f0b0377da0654d5d5e086d69bc0cb94c' 
  AND token = 'asNQhBwRvR5eNXX3xa5q8qxD9gNnRDoYmdCJcxrSs2s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}