SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb4529a097830512a97464265fa73d1f98eca421a3701d23c6aac20e0d846bd3' 
  AND token = 'V5+ptbbRe+KhwUjR94fvBHJ3cROV1dMkKplJeJbvSQ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

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