SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '6fea7027f5c2e3d9e6d71c89a1dccdb19166ebdae9097042934c51889a07b5be' 
  AND token = '0zVsCnS/4UGUmzSIgQV5FNTtBi5DMFcaD/bwBOszYoY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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