SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '586598464ee47458cee393da84d23f2548e7ee35777ea2123b3c3c6df40eac20' 
  AND token = '6O9p/IkzIPOmLNxSEkF6V6wB5adSELhwdekpMyz95Kg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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