SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd5d21ba89c940832b6d617651a093cc376f230401a75c05d98822ffcb013f576' 
  AND token = 'C0IX32jqNxDe/pGXdJl5qdb+atohLHpTxVmTCE80lYw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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