SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5adcc4a2c26ccfbe5548785c13548115ea217416dbb4a5efd0e458fa691a02e' 
  AND token = 'mjk/HHDj2PYD03pUYvyIMoFnvaojiJHm6vA7ubEiKYM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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