SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42dc12d9d42f5c0b807296816787696c7a8dd7171fd47d19c713cc7d3cd85f82' 
  AND token = 'adVGCiZhAVQdjhqjRywbLlcRWjatuv0wxWjdAOT3alQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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