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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52ef3a0b412f67a67cfb7aef72ed17ab6133b203ae9dcbe79576628d3671b6ad' 
  AND token = 'jvvd1MQqeZ5ggQyX/wpZ4agAy+AXcTXa5ymJyfkYIy4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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