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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5d90ce74ea98993ad330daac1e1ccbf0ddf1909b99c4bfeb6a8ccb0b4e8d770a' 
  AND token = 'KiZ60iC3MC+04FUPglnI6O40WhpHMw98z7IZ5aGG0PY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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