SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8921aaefe3f6193e6a41e65750bb796f98bf8daa65ae8b3d45d6e683501be56e' 
  AND token = 'CSkokW0/RTdYnrwfCMP0QPmzayJxPu+OFrqJVpePo7c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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