SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7c47375d8140e867680d88b6b400035423cc4bb1f5fcc3a482dae82f07ce55d' 
  AND token = '4E+NfbQE1ISTEvHC4Be75U8nn+aU7kh+6UF8XftHspk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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