SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '9da546b880e1d65393cd7a20065548427b2eb592b7a491782e303846f086cee2' 
  AND token = 'JfRuVJ+VNk/ThT/X2i/RNd9mPF84EvGO3fXpuZw3A+g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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