SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '45f4bb013e3848e784a19d326b6de852920b29a3b614fbfa3021f2856820de69' 
  AND token = 'FoK2Ix+ZYdEMEFlOEUEjiai3NyhnhPz5j973lQASR9c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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