SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff1e0a72dd0f0216e5134b1057bebec2354a0a9f0fa5f82696976432f90433cc' 
  AND token = 'nkpU2x7BpWSG2kp+8LM8gLKjB2Q8ZVB9X5tnnklfmVo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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