SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '596e60f495b1bea29258a78e4d0255aaa3e66ad145211387c3fa201890ed8e27' 
  AND token = '/3FeCgJKef5zndQVGCJBKN0T1s2GUkqjMUlvzpGf6JQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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