SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a54aa15f56cc8b03b05e6600c5f782d632719cd19fbb0e06e52c798e578f59bb' 
  AND token = 'jqS0Qi5Vf9whZsVOP+tsBVAA8TJOv43QK3HfxVtXng0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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