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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8b04cfe5547760670b229cc77b9f52d0a7f7d242f77c1c0b3bd007199dfd294' 
  AND token = 'MxKxYJKiUXx4Lo+HEWuRTqU5eK/BjZKFsLMwfzcfaw4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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