SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '34fc2cf9ba440a13ec1ca4256c525e2633e691a935163d26d4c83103c2ba66f8' 
  AND token = '1B886/3r74MY9s5pEBaV7irPA5GFJZGPXL0pEs8yWmo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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