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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7ac39b3f8a7e361b5d9acb8f316b13f86a24c79b3c6808c3fe79dd92fd2c724' 
  AND token = 'U2Xjn9yH+yKXzTr6I6siYfobT3l3mvl1Pdtb7yxgoq4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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