SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb8e0a623b191fe5c1a0a37563ec13ba8ae000978da37426b27a90aafc286c34' 
  AND token = 'm+m2h/XJgufejwYzRyVvCaDKkEr1daqlHQo9ycvhLXI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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