SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a42e6f48ec6ccfa7e2b5dea03c9942cfe31485c0b951f9ddcf548006fd6373d8' 
  AND token = 'Coev6/jZMKYYmDiDQB/vzS8gLyLdXx5OV7HVPoFqoKM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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