SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '235c40eac48b84e65941bf146255367e26ab00ab5535fc3159ba887c6dabc8e6' 
  AND token = 'fplNI+ZagcR/Ui3VOcMOKVUOnS96ZcTSgxEZecL2PP0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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