SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9812a35d2ee78aceca9b47d145da3e2e960af1ea405a8fb9d49cf37e4497be5a' 
  AND token = 'hCW1K/nfBcnrVzrnR2rlgUHO9QSumno4zP4DlpwZixs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}