SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '40546c531cfea7c39e70f09d24b1affdf2c2c3dd6733197989f847bade773ad1' 
  AND token = 'W36KaZb64UkwA+DbLuk+0m8jWrlBeaUNga3pWeo4JSo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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