SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '12a05c0c6f6547ed9688626abc6d850f3b7abeeea00af4c8f9b4685c7d8d7d15' 
  AND token = '1jmYSvKwYpA+NIZLlPP5Gv8W2fCTLdFxIWoPVkGFwJ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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