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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c979547ac41ba17636758e7a36732ed8ab741eb7e9f32aa0a2005bbccb04bc65' 
  AND token = 'KyjDW6YkEdsW+NK3nrFxaaG1txB6NXcDSwLUjVz16C0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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