SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a93c09718405498c6258218e1c2e737106d461ee8c27972249e0c1a021b2908' 
  AND token = 'iGhY0u2ErQx+pGLczneQ4XDt91tpAOhTaCEzWKMjoCM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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