SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5051ad83d2d81269650b86d7a19146a7dea865564a6c20e7153b9084225a9d01' 
  AND token = 'gGW2QvmzCdXxhDIilf4dL+SIb1GjO25ChCrazQqwPrw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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