SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29cbf7995a4b1becc1ff2bfb22491012c736edc83b9becccfbad14b87585a4d7' 
  AND token = 'xS6MlVV1Pln+jJarLkEhO2EmVBJ1SGbnP+YQwqQpJRg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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