SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f5f889b467deca025fb539d87698776b0da223704669a58b27aa33bf30debf2' 
  AND token = 'OJnP2Izzxxfj/pAXAFHu5hje/NnwXpUrpVGwcoeFTs4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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