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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f4d6818de593579c4ee2df42f7b4e0145a543a0da7b33675e1578119f2ededf0' 
  AND token = '7iKb4RSZ+9ZCt7w+F4Ph2xOGLyyAF1fcMrYq8SWLQ8s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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