SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2c6783ade3d3f85e07c6ba9ac868e869716e72668041d30a2db6fce5bd844b7f' 
  AND token = '6rfZS8PChD0fP13D6i6d4KkpD63YMm6IV1/YGKg1zHI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}