SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8708bd76ddc0b4742577780cb2a16ef072b4f7f80f0249d70b11578ca70776af' 
  AND token = 'LDhUfzJLlZZSVoLLMIoRE+De++nmUj6ujpR0VrqIQxI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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