SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aa90c96590f5a6a883c1c59eb466b3ff98b42772ceecbfc83e408033bfddaa1a' 
  AND token = 'cXDxdPGY5QeMp1PVk3kwmjcxcZk4wh6UOPwdjaujui4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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