SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '670be97ef1eeb81cbadc2fc44dd43b07a1b3ad6545ffef81078dec72c458437e' 
  AND token = 'JGLkAWZoTdvF7tVTPylMNTLmgOVWcwW2URpg/K2Rbrc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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