SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ecaf0de808b82a2cd9ea5a59ff247dfcc4691dbba41b45a461e25537ed88f8fe' 
  AND token = 's8JpPWHxZ0A+/ZuRc3I1UVWEHR1cxyVC1lyNlkPEU28=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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