SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b55ad23fa9c5575d2740e58118a6211c456fa6b5f3afd59b5c25b2edd98d3ad9' 
  AND token = 'JptCDxeo9JuUUlbAwNEHCPoYvRfGumxAlLbWWS9Q1Co=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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