SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c24e55757ea1dce89e4b2e5605460775b55cd64a7936997fb58dca01b850d75a' 
  AND token = 'RDg0wA4aPyT8uLgdxDNxYkeORzqmOTgFMIP99fVfgck=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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