SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '41b3d4c49780950dffa609494ae4853110647acd10b85910d8e877d5b7bdf175' 
  AND token = 'ot5BFCF+wp6XxevQwNuyAMFoWgDVtMzGjCjKTJDFccU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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