SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c8903ef9356ef3d4ec610332246607b7fe5ca6f8919b97a1588c8486a865372' 
  AND token = '7mhXq0iBb7+RRfYHkdp82UqKWmL+OnjB3YGrMo9/vps=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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