SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f12d4602c9784d303c3cfaa0cfac59498f645e623c2dc3b4f020256682a1b4f8' 
  AND token = 'UQ6Vz0+GYT7ejJF/ERV0ijvqZb+gkbFnN2l2XJN57AA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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