SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f09c5e052cb60cc6185d024c427ddd5c052961a74cadef091994e7eaf6673282' 
  AND token = 'pr8qsfA/pafI/HnGHx9TYoh3sh9nyJvYecDm4/K+uKM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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