SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '831d6f68503a7ecea7dc91ea0051edcec003254e699a6b4f0d437bbee6fabc12' 
  AND token = 'ia2lmF6AMw8ls8+B6fV71XQiTysfi/2eq5v9cu1MYrw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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