SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e53a26ff5ee84114c83d591404133d170be70d9fca777665b8fb229267622edc' 
  AND token = 's/BEXKsAMyGH9lM98qd0jnh7ORVi90imlnZuCwUntGM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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