SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '6742ed656502cf2a90a0ef52ad021fba7db06f3e0c853c3e2e00f7f49dcf5119' 
  AND token = 'MYYd+LzqER5AsubVNoASXmv1c/OUKyjsZ0Qv+VGyRZI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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