SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68f356e17c4fc14585781a475c921abb8a72c4247a4752135c67f8dfdc66765f' 
  AND token = 'feNojqCXXvd3ZG/vuQupXUSEHyL290qjv2LdrnJB9dQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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