SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8639d6e0b0e89a154fde2509eba430645d924e33acb4f70f46608adff9e2b0e' 
  AND token = '75aJA9HZ5FywgEbuBKIzqfYYcqFHNRRJlUkqqr7sUEE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

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