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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ebff9f7d4b8e705dcbe95efb82f43b9b9a6df117f039a9cd30d8960a29603d5a' 
  AND token = 'kJZcEsWuH0X2ryjoiEmdO9mRlWl+Q1Jk4l91qeOW7VA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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