SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe5bdef521b5b2a7f623dc85b085a16f6f0e6841dc50394153c01a9893a0fb7f' 
  AND token = 'kL//Tz469BHhlPpSuTgqKSNvEsMYFqbayJzow5XMpg0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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