SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '19f78bd86eb17df3df6cdafb0b53855afc6430a9e15094dd85e378b3c74a7d9c' 
  AND token = 'QgzmsMohChLYjbNmzXbq3Z2v6UkBejUDQrWoTGYPMb0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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