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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3475fdfdea22d93546cb5ccd7fcb31205e8836de1a4479a7e8350254ac21218e' 
  AND token = 'mvXUKCi7z4atcD9HibAjEhj2uinO+NTVLcxO/uQwfPw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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