SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2dc5516242440eaa06c2a00c9703bb8955f980598c832d934b0b50d12b80e3c2' 
  AND token = 'SNAOsiUK5JxRXwAxR+E1DPWMvKfVDoR5AAFN87D4yEg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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