SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2604e7e3f995c385a291ab573749e10d617e1c2d8620f4dcda4f581e49a3adae' 
  AND token = 'z9D83/GtKxtgLowVW6XFN2POVcPLA4JBP8sSf+oqahQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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