SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '642ef36b95e262c69fe731ee8516abcddd023a941d2c145c3d6f0be05d1f5878' 
  AND token = 'CksHO8K8hH4sNwVYrmzPUXPaSlaMqHSmljC+2CHlqYk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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