SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3c374b631a1d90664d41872a003c89c7afa083fcb301b6e0aa1ee1b167a6c34' 
  AND token = 'BDmeVL1fFbyelPqbHFkz0vLqrGOl0/J8FpUd2uabtXo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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