SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1f3646eae2a902a39bd71a320604338dd3b4fcb8541a3ed9e48b83de57090fec' 
  AND token = 'ajn89o+8Z8bHsYL4cyfaPCz3zNMgMs4QZ0FzaDF3Rdo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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