SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b4ef690a9c9bf50c80ecd5ee523e2fcfa806acfbc83c1d363739a2acffbe076' 
  AND token = 'ejLoMppPKHxF2EKJKu0toCcN3NrEMT5PcA7Kr1JEB3w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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