SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f615ca088c972408647638c40d60b467f0d9a5f298f026dd26320c22f1972bd0' 
  AND token = '8iX9bcRbLoN47WEAkTGu/VepAo3EMXfvq3h4vOiAO6g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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