SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6787a534395f5f64203f4ee69caa2aec72b43bd6a408c47eccb358697e9ed0e' 
  AND token = '9MNgot4lU0UnnUeVkkFtGHIEcnOhuBnBiSNo/OS6s5I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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