SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '121abdd967464afaf0a9a6287753ec0aef5d630238ca86a2b7eb309a082a7190' 
  AND token = 'BhA0m/B1fWxVhhGmvhv7mw0CHR5aUqydMfszkDQxZzU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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