SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a08447e0b0886b4b67b90bc149053230fc028f1eb450aa1acd6d83cd71c4d7e6' 
  AND token = 'XxP8sTjbiiwW4wV24rMkptHR+Q2rb3hb8B+tbEjaBBc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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