SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '6d21082fdc52a384f8736e31071897550f3199abf3a6f5c64090f6dec7c195cb' 
  AND token = 'vXf3axIbgLoEO43peyNZRt14PKQEpPLOdx17ToyCewY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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